bpf: add helper bpf_perf_prog_read_value

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This patch adds helper bpf_perf_prog_read_cvalue for perf event based bpf
programs, to read event counter and enabled/running time.
The enabled/running time is accumulated since the perf event open.

The typical use case for perf event based bpf program is to attach itself
to a single event. In such cases, if it is desirable to get scaling factor
between two bpf invocations, users can can save the time values in a map,
and use the value from the map and the current value to calculate
the scaling factor.

Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

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Yonghong Song 2017-10-05 09:19:22 -07:00 • committed by David S. Miller

parent 020a32d958

commit 4bebdc7a85

2 changed files with 37 additions and 1 deletions

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10

include/uapi/linux/bpf.h

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28

kernel/trace/bpf_trace.c

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